Doesn’t matter if it’s a new server or not. If is was a leak, it would have been your Plex account info. Are you using Tautulli and enabled it for remote access? There is a some sort of security setting that you can and should enable. Without this, someone could gain access to Tautulli and then get your Plex account info.
Here is a link to some more info on this issue. Unauthorised Access to Plex Sharing - #4 by OttoKerner
